Roles of nanomaterial structure and surface coating on thin film nanocomposite membranes for enhanced desalination

Abstract

In this work, two types of thin film nanocomposite (TFN) membranes were developed (by incorporating either 0.05 wt/v% surface-modified nanoporous titanium oxide (f-nTiO2) or titanate nanotube (f-TNT) in the polyamide selective layer) to investigate the impacts of nanomaterial structures (i.e., sizes and shapes) on membrane properties and desalination performances. The filtration results revealed that the incorporation of f-nTiO2 yielded membrane of better filtration performances than the one incorporated with f-TNT. Compared to the TFN-f-TNT membrane, the TFN-f-nTiO2 membrane possessed greater water flux (4.26 vs. 3.36 L/m2 h bar) and higher NaCl (98.04 vs. 97.28%) and boron rejection (54.82 vs. 48.86%). It was also found that surface coating of TFN membranes with hydrophilic polyvinyl alcohol could further improve membrane solute rejection (up to 9%) with slight reduction in water flux.